Mask breather valve



FIG. 1 is a front elevation view of a mask breather valve, showing mydesign.

FIG. 2 is a rear elevation view thereof.

FIG. 3 is a left side elevation view thereof.

FIG. 4 is a right side elevation view thereof.

FIG. 5 is a bottom plan view thereof.

FIG. 6 is a top plan view thereof.

FIG. 7 is front perspective view thereof.

FIG. 8 is rear perspective view thereof; and,

FIG. 9 is perspective view of the mask breather valve with the valvehalf open.

The broken lines illustrate portions of the mask breather valve thatform no part of the claimed design.

CLAIM The ornamental design for a mask breather valve, as shown anddescribed.